One of the fundamental aspects of Rosh Hashana is the Shofar. But is it really? Perhaps the Shofar itself is not fundamental to the Chag at all. Rather, one might claim that it is the sound that is emitted from the Shofar which is integral and not the Shofar itself.
In addressing this issue, Rav Moshe Lichtenstein quotes various rabanim. However, he raises a further question: Must the Shofar be straight or can it be bent? In order to answer this question, one is brought right back to the initial query. Is the Shofar itself, the physical part of the Shofar, important, or is it the sound which comes out which is the essential factor? Rav Moshe Lichtenstein says that if the Shofar is present on Rosh Hashana for the carnation or exaltation of God, then it would be proper and better for the Shofar to be straight since a straight Shofar is more perfect in appearance.
However, if the Shofar is present only because it must be blown, meaning that only the sound is important, then it would seem that it would be okay to use a curved Shofar. Rav Lichtenstein quotes a Machloket between the Rambam and the Ramban. The Rambam believes that it is the sound which is the primary aspect to the Mitzva while the Ramban says that it is the Shofar itself which is primary. If the goal in using the Shofar on Rosh Hashana is in fact not the carnation or exaltation of God, but rather to achieve Teshuva, then the Shofar should be bent because we are not perfect, rather, we are bent and we are trying to do Teshuva to "straighten ourselves out."
The sounds of the Shofar should remind us to do Teshuva. If so, shouldn't everybody be obligated to blow? Therefore the opinion of the Rambam would seem to be correct.
On Rosh Hashana, one should listen to the sounds of the Shofar and remember that this is the time when he is being judged by Hashem and he should focus on his inner self. One should focus his thoughts on his past actions and focus on his future goals. By doing this, he is mending his relationship with Hashem and setting himself up for a better judgement.